Abstract：
Acoustics of bubbles is quite developed field mainly due to multiple cavitation-related ultrasonic applications in liquids. New applications, which require detailed studies of ultrasound encounter with bubble in solid materials, have become apparent recently and are concerned with detectability of porosity in advanced solid materials based on layered technology, like composite and additive manufactured structures. To elucidate the transition from liquids to solids the present paper starts from theoretical similarity between both and proceeds to experimental study of the resonance acoustic effects of air bubbles in epoxy resin. The LDR frequencies are shown to be reciprocal to the bubble radius so that the latter can be evaluated if the frequency is known. The bubbles excited at the LDR frequencies and their subharmonics (superharmonic resonance) manifest extraordinary wide higher harmonic spectra that implies a nonlinear means for nondestructive testing of porosity in composites and other materials.
摘要：
气泡声学是相当发达的领域，主要是由于多个空化相关的超声波在液体中的应用。新应用,这需要详细研究超声波在固体材料中与气泡的接触，最近已经变得明显，并且关注基于分层技术的先进固体材料中孔隙率的可检测性，如复合材料和增材制造结构。为了阐明从液体到固体的转变，本文从两者之间的理论相似性开始，并进行了环氧树脂中气泡共振声学效应的实验研究。LDR频率显示为与气泡半径倒数，因此如果频率已知，则可以评估气泡半径。在LDR频率下激发的气泡及其次谐波（超谐波共振）表现出非常宽的高次谐波谱，这意味着用于对复合材料和其他材料中的孔隙率进行无损检测的非线性手段。
